In many situations, there is a need to know whether a particular temperature has been achieved. For example, one may be interested when cooking food that the food has exceeded a particular temperature. This can be associated with a particular taste in food, whether rare, medium, or well done, whether one has cooked the food sufficiently to ensure that any organisms have been killed, or the like. In fast food restaurants, it would be particularly convenient to have a simple throw away device which would allow for the determination that the food has been cooked sufficiently to ensure the substantial killing of any organisms.
In cooking, there are many situations where it is necessary to achieve a certain temperature in order to obtain the desired result. For example, syrups used in butter creams are required to be heated to a specific temperature, before they are emulsified with butter. The thermometers which find use for this and other purposes are usually large, bulky, inconvenient, and allow for too much contact with the pot, which may be at a different temperature from the contents in the pot. In baking, there is no convenient way today to determine the internal temperature of a cake or pudding.
There has also been concern about the temperature of hot liquids, where legal recoveries have been obtained where people have been scalded. For baby formulas, one desires to determine whether the temperature has the desired temperature to ensure that the formula is safe. Again, if one had a simple technique to establish whether the liquid has exceeded a safe temperature, these problems may be avoided.
Not only would disposables find use with food, but they could also be used in conjunction with areas which may become unexpectedly heated such as electrical implements, processing equipment, hot water or other heaters, electric and gas ranges, microwave ovens and food heated in the ovens, etc.
Desirably, the devices should be very inexpensive, easily manipulated, provide for a clear and objective determination that the temperature has been reached, and disposable.
Diacetylenes have been used for determining temperature, as described in U.S. Pat. Nos. 4,339,951, 4,721,769, 5,085,801, and references cited therein. However, all of these devices have disadvantages in their application for the purposes described above.